I think the White House misunderstood what people were going for on this. I know the petition says FREE Steven Avery, but I think all people really wanted was a retrial. Anyhoo, here’s the response, posted from Change.org:
“Jan 8, 2016 — This response was posted by the We The People Team at the White House:
Thank you for signing a Change.org petition on the Teresa Halbach murder case, currently featured on the “Making a Murderer” documentary series. We appreciate your interest in this case.
To best respond to your petition, we should go over what exactly presidential pardoning power entails.
The U.S. Constitution grants the power of clemency to the President:
“The President … shall have Power to Grant Reprieves and Pardons for Offenses against the United States.”
This clemency authority empowers the President to exercise leniency towards persons who have committed federal crimes. Under the Constitution, only federal criminal convictions, such as those adjudicated in the United States District Courts, may be pardoned by the President. In addition, the President’s pardon power extends to convictions adjudicated in the Superior Court of the District of Columbia and military court-martial proceedings. However, the President cannot pardon a state criminal offense.
Since Steven Avery and Brendan Dassey are both state prisoners, the President cannot pardon them. A pardon in this case would need to be issued at the state level by the appropriate authorities.